Metal-organic framework materials comprising a pyrazolylbenzoate ligand and methods for production thereof

Abstract

Metal-organic framework materials (MOFs) are highly porous entities comprising a multidentate organic ligand coordinated to multiple metal centers, typically as a coordination polymer. Some highly porous MOFs lack stability at ambient conditions. MOFs having ambient condition stability may comprise a plurality of metal clusters (M 4 O clusters, M=a metal), and a plurality of 4-(1H-pyrazol-4-yl)benzoate ligands coordinated to the plurality of metal clusters to define an at least partially crystalline network structure having a plurality of internal pores. Methods for synthesizing these MOFs may comprise combining a metal source, such as a preformed metal cluster, with 4-(1H-pyrazol-4-yl)benzoic acid, and reacting the preformed metal cluster with the 4-(1H-pyrazol-4-yl)benzoic acid to form a MOF having an at least partially crystalline network structure with a plurality of internal pores defined therein and comprising a plurality of metal clusters coordinated to a multidentate organic ligand comprising 4-(1H-pyrazol-4-yl)benzoate.

The invention claimed is: 
     
       1. A metal-organic framework material comprising:
 a plurality of metal clusters comprising one or more M 4 O clusters, wherein M is a metal and at least a portion of the plurality of metal clusters comprise zinc; and 
 a plurality of multidentate organic ligands coordinated to the plurality of metal clusters to define an at least partially crystalline network structure having a plurality of internal pores, the multidentate organic ligand comprising 4-(1H-pyrazol-4-yl)benzoate, 4-(3,5-dimethyl-1/-pyrazol-4-yl)benzoate, or a combination thereof, 
 wherein the at least partially crystalline network structure has a BET surface area of about 2800 m 2 /g to 3700 m 2 /g. 
 
     
     
       2. The metal-organic framework material of  claim 1 , wherein at least a portion of the plurality of metal clusters has a tetrahedral geometry. 
     
     
       3. The metal-organic framework material of  claim 1 , wherein at least a portion of the plurality of metal clusters further comprise cobalt, nickel, copper, iron, chromium, manganese, or any combination thereof. 
     
     
       4. The metal-organic framework material of  claim 1 , wherein the at least partially crystalline network structure exhibits an x-ray powder diffraction pattern consistent with a cubic space group. 
     
     
       5. The metal-organic framework material of  claim 1 , wherein the metal-organic framework material is a reaction product of a preformed metal cluster and the 4-(1H-pyrazol-4-yl)benzoate, the 4-(3,5-dimethyl-1H-pyrazol-4-yl)benzoate, or the combination thereof. 
     
     
       6. The metal-organic framework material of  claim 5 , wherein the preformed metal cluster comprises Zn 4 O(2,2-dimethylbutanoate) 6 . 
     
     
       7. The metal-organic framework material of  claim 1 , wherein the internal pores have pore diameters in a range of about 10 Å to about 20 Å. 
     
     
       8. The metal-organic framework material of  claim 1 , wherein the internal pores have a pore volume in a range of about 0.9 cc/g to about 1.5 cc/g. 
     
     
       9. The metal-organic framework material of  claim 1 , wherein the at least partially crystalline network structure has an x-ray powder diffraction pattern having characteristic peaks of at least 6.21, 8.76, 12.40, and 13.83 (all ±5%) degree 2-theta (°2θ). 
     
     
       10. A method comprising:
 contacting a mixture comprising one or more chemical species with the metal-organic framework material of  claim 1 , and 
 sorbing at least a portion of the one or more chemical species into at least a portion of the internal pores. 
 
     
     
       11. The method of  claim 10 , wherein the one or more chemical species comprises methane. 
     
     
       12. A method comprising:
 combining a metal source with 4-(1H-pyrazol-4-yl)benzoic acid, 4-(3,5-dimethyl-1H-pyrazol-4-yl)benzoate, or a combination thereof; and 
 reacting the metal source with the 4-(1H-pyrazol-4-yl)benzoic acid, the 4-(3,5-dimethyl-1H-pyrazol-4-yl)benzoate, or the combination thereof to form a metal-organic framework material, 
 wherein the metal source is a preformed metal cluster that comprises Zn 4 O(2,2-dimethylbutanoate) 6 . 
 
     
     
       13. The method of  claim 12 , the method further comprising:
 exchanging at least a portion of a first metal comprising the plurality of metal clusters for a second metal.